Expandable cage

ABSTRACT

An apparatus supports the spine between vertebrae and promotes spinal fusion. The apparatus generally includes a first supporting member, a second support member, and an expansion member. The first support member has a first longitudinal passage extending therethrough, a first supporting end configured to engage tissue, and a rack configured to engage a tool. The second supporting member contains a second longitudinal passage extending therethrough and a second supporting end configured to engage tissue. The second longitudinal passage is dimensioned to receive at least a portion of the first supporting member. The first and second supporting members are configured to move with respect to each other. The expansion member is removably positioned between the first and second supporting members and is adapted to maintain the first and second supporting members in a fixed relative position.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 12/602,868, filed Dec. 3, 2009, which claims priority to, andthe benefit of, U.S. Provisional Patent Application No. 61/072,176,filed on Mar. 28, 2008, and U.S. Provisional Patent Application No.61/087,046, filed on Aug. 7, 2008, the contents of each of these priorapplications are incorporated by reference herein in their entirety.

BACKGROUND

Technical Field

The present disclosure relates to apparatus and methods for treatingspinal conditions and, more particularly, for supporting adjacentvertebrae.

Background of Related Art

The human spine includes thirty-three vertebrae. The vertebrae interlockwith one another to form a spinal column. Each vertebra has acylindrical bony body (vertebral body), two pedicles extending from thevertebral body, a lamina extending from the pedicles, two wing-likeprojections extending from the pedicles, a spinous process extendingfrom the lamina, a pars interarticularis, two superior facets extendingfrom the pedicles, and two inferior facets extending from the lamina.The vertebrae are separated and cushioned by thin pads of tough,resilient fiber known as inter-vertebral discs. Inter-vertebral discsprovide flexibility to the spine and act as shock absorbers duringactivity. A small opening (foramen) located between each vertebra allowspassage of nerves. When the vertebrae are properly aligned, the nervespass through without a problem. However, when the vertebrae aremisaligned or a constriction is formed in the spinal canal, the nervesget compressed and may cause back pain, leg pain, or other neurologicaldisorders.

Disorders of the spine that may cause misalignment of the vertebrae orconstriction of the spinal canal include spinal injuries, infections,tumor formation, herniation of the inter-vertebral discs (i.e., slippageor protrusion), arthritic disorders, and scoliosis. In these pathologiccircumstances, surgery may be tried to either decompress the neuralelements and/or fuse adjacent vertebral segments. Decompression mayinvolve laminectomy, discectomy, or corpectomy. Laminectomy involves theremoval of part of the lamina, i.e., the bony roof of the spinal canal.Discectomy involves removal of the inter-vertebral discs. Corpectomyinvolves removal of the vertebral body as well as the adjacentinter-vertebral discs.

A number of spinal surgical devices may be used to promote bony fusionafter decompressing the spinal nerves. For instance, surgeons oftenreplace the diseased vertebral tissue with one or more spinal cages andbone support matrix. Spinal cages support adjacent vertebral segments,while furthering spinal fusion of adjacent vertebral bodies. Scientistsand clinicians have developed a number of devices and methods fordecompressing spinal nerves. Improvements to this methods and devicesare nevertheless still possible.

SUMMARY

The present disclosure relates to an apparatus for supporting adjacentvertebrae and promoting spinal fusion. The apparatus generally includesa first supporting member, a second support member, and an expansionmember. The first support member has a first longitudinal passageextending therethrough, a first supporting end configured to engagetissue, and a rack configured to engage a tool. The second supportingmember contains a second longitudinal passage extending therethrough anda second supporting end configured to engage tissue. The secondlongitudinal passage is dimensioned to receive at least a portion of thefirst supporting member. The first and second supporting members areconfigured to move with respect to each other. The expansion member isremovably positioned between the first and second supporting members andis adapted to maintain the first and second supporting members in afixed relative position.

In addition to the apparatus, the present disclosure relates to a methodfor supporting adjacent vertebrae. This method includes the followingsteps: (1) providing an apparatus including first and second supportingmembers configured to move relative to each other and an expansionmember removably positioned between the first and second supportingmembers, the first supporting member including a rack disposed along aninner surface thereof, wherein the second supporting member defines alongitudinal passage adapted to receive at least a portion of the firstsupporting member; (2) providing a driver configured to engage the rackof the first supporting member; wherein first and second supportingmembers are adapted to move relative to each other upon rotation of thedriver when the driver is operably engaged with the rack; (3) removingvertebral tissue; (4) inserting the apparatus between adjacentvertebrae; (5) engaging the driver with the rack; (6) actuating thedriver with the driver in engagement with the rack to adjust a relativeposition of the first and second supporting members; and (7) positioningthe expansion member between the first and second supporting members tomaintain the relative position of the first and second supportingmembers; and (8) disengaging and removing the driver.

The present disclosure further relates to a tool for inserting anexpandable cage inside a body. This tool includes an insertion portionadapted to position an expandable cage inside a body, a driver foradjusting a height of the expandable cage, and a holding portionconfigured to hold the expandable cage. The holding portioninterconnects the insertion portion and the driver. The driver isrotatably mounted on the holding portion.

In addition, the present disclosure relates to a tool assembly forinserting an expandable cage inside a body. This tool assembly includesa handle, an elongate section extending from the handle, a holdingsection operatively coupled to the elongate section, a rod extendingthrough the elongate section and the holding section, and a barpartially disposed within the holding section. The rod includes athreaded tip positioned at a distal portion thereof. The threaded tipprotrudes distally from the holding section and is configured to rotaterelative to the elongate section. The bar includes a head having aplurality of teeth and is configured to rotate relative to the holdingsection.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of an expandable cage according to anembodiment of the present disclosure with an expansion member securedbetween the first and second supporting members;

FIG. 2 is a perspective view of the expandable cage of FIG. 1 with theexpansion member partially removed from its secured position between thefirst and second supporting members;

FIG. 3 is perspective exploded view of the expandable cage of FIG. 1;

FIG. 4 is a right side view of the expandable cage of FIG. 1, showingsection line 9-9;

FIG. 5 is a perspective view of the expansion member of the expandablecage of FIG. 1;

FIG. 6 is a top view of the expandable cage of FIG. 1;

FIG. 7 is a front view of the expandable cage of FIG. 1;

FIG. 8 is a bottom view of the expandable cage of FIG. 1;

FIG. 9 is a cross-sectional view of the expandable cage of FIG. 1, takenalong section line 9-9 of FIG. 4;

FIG. 10 is a perspective view of an insertion tool holding theexpandable cage of FIG. 1 without the expandable member;

FIG. 11 is a front view of the insertion tool of FIG. 10 holding theexpandable cage of FIG. 1 without the expansion member;

FIG. 12 is a cross-sectional view of the insertion tool of FIG. 10holding the expandable cage of FIG. 1 without the expansion member,taken along section line 12-12 of FIG. 11;

FIG. 13 is a top view of a distal portion of the insertion tool of FIG.10 holding the expandable cage of FIG. 1 without the expansion member;

FIG. 14 is a cross-sectional view of the insertion tool of FIG. 10holding the expandable cage of FIG. 1 without the expansion member,taken along section line 14-14 of FIG. 13;

FIG. 15 is a rear perspective view of an expandable cage according to analternate embodiment of the present disclosure with an expansion membersecured between the first and second supporting members;

FIG. 16 is a front view of the expandable cage of FIG. 15;

FIG. 17 is right side view of the expandable cage of FIG. 15;

FIG. 18 is a top view of the expandable cage of FIG. 15;

FIG. 19 is a bottom view of the expandable cage of FIG. 15;

FIG. 20 is a front perspective view of the expandable cage of FIG. 15;

FIG. 21 is a front perspective view of the expandable cage of FIG. 15with the expansion member separated from the expandable cage;

FIG. 22 is a perspective exploded view of the expandable cage of FIG.15;

FIG. 23 is a perspective view of the expansion member of the expandablecage of FIG. 15;

FIG. 24 is a perspective view of a driver according to an embodiment ofthe present disclosure;

FIG. 25 is an enlarged sectional view of a distal portion of the driverof FIG. 24, taken around section 25 of FIG. 24;

FIG. 26 is a perspective exploded view of the driver of FIG. 24;

FIG. 27 is an enlarged sectional view of the distal portion of thedriver of FIG. 24, taken around section 27 of FIG. 26;

FIG. 28 is a top view of the driver of FIG. 24;

FIG. 29 is a cross-sectional view of the driver of FIG. 24; taken alongsection line 29-29 of FIG. 28;

FIG. 30 is an enlarged sectional view of a proximal portion of thedriver of FIG. 24; taken around section 30 of FIG. 28;

FIG. 31 is an enlarged sectional view of the distal portion of thedriver of FIG. 24, taken around section 31 of FIG. 28;

FIG. 32 is a side view of the driver of FIG. 24 holding an expansionmember of FIG. 23;

FIG. 33 is a top view of the driver of FIG. 24 holding the expansionmember of FIG. 23;

FIG. 34 is an enlarged side view of the distal portion of the driver ofFIG. 24 holding the expansion member of FIG. 23, taken around section 34of FIG. 32;

FIG. 35 is an enlarged top view of the distal portion of the driver ofFIG. 24 holding the expansion member of FIG. 23, taken around section 35of FIG. 33;

FIG. 36 is a perspective view of an insertion tool according to anotherembodiment of the present disclosure;

FIG. 37 is an enlarged perspective view of a distal portion of theinsertion tool of FIG. 36, taken around section 37 of FIG. 36;

FIG. 38 is a side view of the insertion tool of FIG. 36;

FIG. 39 is a side cross-sectional view of the insertion tool of FIG. 35,taken along section line 39-39 of FIG. 38;

FIG. 40 is an enlarged side cross-sectional view of the distal portionof the insertion tool of FIG. 36, taken around section 40 of FIG. 39;

FIG. 41 is a side cross-sectional view of the distal portion of theinsertion tool of FIG. 36, taken along section line 41-41 of FIG. 38;

FIG. 42 is a front view of the insertion tool of FIG. 36;

FIG. 43 is an enlarged front view of the insertion tool of FIG. 36,taken around section 43 of FIG. 42;

FIG. 44 is a side view of the insertion tool of FIG. 36;

FIG. 45 is an enlarged side view of the distal portion of the insertiontool of FIG. 44, taken around section 45 of FIG. 44;

FIG. 46 is a side cross-sectional view of a proximal portion of theinsertion tool of FIG. 36, taken around section 46 of FIG. 39;

FIG. 47 is a perspective exploded view of the insertion tool of FIG. 36;

FIG. 48 is a perspective exploded view of the distal portion of theinsertion tool of FIG. 36;

FIG. 49 is a rear view of the insertion tool of FIG. 36 holding theexpandable cage of FIG. 15;

FIG. 50 is a side cross-sectional view of the distal portion of theinsertion tool of FIG. 36 holding the expandable cage of FIG. 15, takenaround section 52 of FIG. 51;

FIG. 51 is a perspective view of the driver of FIG. 24 and the insertiontool of FIG. 36 holding the expandable cage of FIG. 15;

FIG. 52 is a top view of the distal portion of the insertion tool ofFIG. 36 holding the expandable cage of FIG. 15; and

FIG. 53 is a front cross-sectional view of the distal portion of theinsertion tool of FIG. 36 holding the expandable cage of FIG. 15, takenalong section line 53-53 of FIG. 52.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the presently disclosed devices and methods will now bedescribed in detail with reference to the drawings, wherein likereference numerals identify similar or identical elements. In thedrawings and in the description that follows, the term “proximal” willrefer to the end of a tool or device that is closest to the operator,while the term “distal” will refer to the end of the tool or device thatis farthest from the operator. In addition, the term “cephalad” is usedin this application to indicate a direction toward a patient's head,whereas the term “caudad” indicates a direction toward the patient'sfeet. Further still, for the purposes of this application, the term“medial” indicates a direction toward the middle of the body of thepatient, whilst the term “lateral” indicates a direction toward a sideof the body of the patient (i.e., away from the middle of the body ofthe patient). The term “posterior” indicates a direction toward thepatient's back, and the term “anterior” indicates a direction toward thepatient's front. As used herein, a “bone support matrix” is a materialthat facilitates new bone growth between the opposing vertebral bodies.Suitable bone support matrices can be resorbable or nonresorbable andosteoconductive or osteoinductive. Examples of suitable bone supportmatrices include synthetic materials, bone morphogenic proteins (BMPs),and heterologous, homologous, or autologous bone and derivativesthereof. The bone support matrix may be radiolucent on x-rays.

FIGS. 1 and 2 show an expandable cage 10 designed for supportingadjacent vertebra and promoting spinal fusion. Expandable cage 10, whichmay be made of autologous bone graft, bone allograft,polyetheretherketone (PEEK), titanium, stainless steel, cobalt chrome,polymeric materials, a combination thereof, or any other suitablematerial, includes first and second supporting members 12, 14 configuredto move relative to each other and an expansion member 16 removablypositioned between first and second supporting members 12, 14.Expandable cage 10 may be part of a kit including first and secondsupporting members 12, 14 and several expansion members 16 of differentsizes. The different expansion members 16 are dimensioned to maintainfirst and second supporting members 12, 14 in different relativepositions. The plurality of expansion members 16 allows a user to adjustand fix expandable cage 10 at different heights. During operation, theuser can adjust the relative position of first and second supportingmembers 12, 14 to accommodate expandable cage 10 in a variable spacelocated between adjacent vertebrae. After placing expandable cage 10 insuch space, the user positions the appropriate expansion member 16between first and second supporting members 12, 14 to maintain theirrelative position, thus fixing the expandable cage 10 at the desiredheight.

With reference to FIGS. 3 and 9, first supporting member 12 ofexpandable cage 10 includes a first supporting end 20 and an elongatebody 18 extending from first supporting end 20. As seen in FIG. 3,elongate body 18 may be a C-shaped structure. It is envisioned, however,that elongate body 18 may have any suitable structure, shape orconfiguration. Regardless of its shape, elongate body 18 defines alongitudinal passage 22 extending therethrough. Longitudinal passage 22is adapted to receive optional autologous bone graft, bone allograft,bone slurry, bone chips, bone morphogenic protein or any other bonesupport matrix suitable for promoting bony union between vertebrae. Inthe embodiment depicted in FIG. 3, first, second, and third walls 28,30, 32 collectively define longitudinal passage 22 and form elongatebody 18. Each of first, second and third walls 28, 30, 32 have flatouter surfaces. Second wall 30 interconnects first and third walls 28,32. First wall 28 is transversely secured to second wall 30, whilesecond wall 30 is transversely attached to third wall 32. First andthird walls 28, 32 are arranged in parallel with respect to each other.Second wall 30, on the other hand, is arranged in a substantiallyorthogonal relationship with first and third walls 28, 32.

First wall 28 contains a slot 34 disposed along an outer surfacethereof, as depicted in FIG. 9. Slot 34 is configured to slidablyreceive a pin 36. Slot 34 and pin 36 jointly allow first and secondsupporting members 12, 14 to slide relative to each other whilemaintaining alignment of the parts, inhibiting relative rotationalmovement of the parts, and inhibiting separation of the parts. Inaddition to slot 34, first wall 28 includes a plurality of undulationsor indentations 42 spreading along an inner surface thereof. Undulations42 together form rack 66 configured to engage a head 122 of an insertiontool 100. (See for example FIGS. 12 and 14). Third wall 32 features aslot 38 formed along an outer surface thereof. Slot 38 is adapted toslidably receive a pin 40. Slot 38 and pin 48 cooperatively allow firstand second support members 12, 14 to slide with respect to each otherwhile maintaining alignment of the parts, inhibiting relative rotationalmovement of the parts, and inhibiting separation of the parts.

With reference to FIGS. 3 and 8, first supporting end 20 includes anengagement surface 24 and an abutting surface 26 disposed in directlyopposite relation with respect to each other. Abutting surface 26 facessecond supporting member 14, whereas engagement surface 24 faces awayfrom second supporting member 14, when second support member 14 is atleast partially placed over first supporting member 12. Engagementsurface 24 contains a plurality of teeth 44 adapted to engage avertebra, or any other kind of tissue, and a recess 46 disposed around acentral area thereof. Teeth 44 are arranged in longitudinal rowsspreading along the width of engagement surface 24. Each tooth 44defines an oblique angle in relation to the abutting surface 26, as seenin FIG. 4. Nonetheless, engagement surface 24 may alternatively haveteeth 44 having other configurations and arrangements or any otherstructure capable of engaging tissue. Recess 46 has a substantiallyrectangular shape and is configured to receive any suitable bone supportmatrix to promote spinal fusion between adjacent vertebrae.

As seen in FIG. 8, first supporting member end 20 further includes atleast one hole 48 disposed in recess 46. Hole 48 extends through firstsupporting end 20 and provides access to longitudinal passage 22 (FIG.3). During use, bone support matrix enters longitudinal passage 22 (seeFIG. 3) through hole 48. In the embodiment depicted in FIG. 8, firstsupporting end 20 includes six (6) holes 48 having circularcross-sections and arranged in longitudinal rows. First supporting end20, however, may have fewer or more holes 48. Furthermore, holes 48 mayhave any other suitable configuration or arrangement.

As shown in FIGS. 1 and 4, first supporting end 20 additionally includescavities 50, 52 disposed on opposite lateral sides 54, 56 thereof. Eachcavity 50, 52 (FIGS. 1 and 4) is adapted to receive arms 118 of aninsertion tool 100. (See FIGS. 10 and 13). During operation, a user mayadvance expandable cage 10 toward the desired surgical site bypositioning arms 118 of an insertion tool 100 (See FIG. 10) withincavities 50, 52 of first supporting end 20 and advancing insertion tool100 toward the surgical site.

Referring again to FIG. 3, first supporting end 20 includes an abutmentsurface 26, as discussed above. Abutment surface 26 interconnects first,second, and third walls 28, 30, 32 and abuts at least a portion ofexpansion member 16 when expansion member 16 is placed between first andsecond supporting members 12, 14. To facilitate a secure connectionbetween first and second supporting members 12, 14, abutment surface 26includes a locking recess 58 adapted to securely receive a lockingportion 60 of a backspan 59 of expansion member 16. Locking portion 60defines an opening 73 for allowing access of bone support matrix intolongitudinal passage 22. Aside from locking portion 60, expansion member16 includes a pair of legs 62 extending transversely with respect tobackspan 59 which includes locking portion 60. Locking portion 60 isconfigured to securely engage locking recess 58 of first supportingmember 12 and a locking recess 64 formed on second supporting member 14.Altogether, locking portion 60 and locking recesses 58, 64 form adovetail joint with a locking mechanism 68. Locking mechanism 68 may be,for example, a snap-fit coupling; however, locking mechanism 68 mayinclude any other suitable coupling configured to connect expansionmember 16 to first and second supporting members 12, 14.

As seen in FIGS. 2, 3 and 5, in one embodiment, locking portion 60 ofbackspan 59 includes first and second snap-fit arms 61, 63. First andsecond snap-fit arms 61, 63 are disposed on directly opposite surfacesof the backspan 59 relative to each other. Each of the first and secondsnap-fit arm 61, 63 are pivotally (or hingedly) connected to lockingportion 60 at one end, i.e., cantilevered. First snap-fit arm 61 isadapted to be releasably coupled to locking recess 58 of firstsupporting end 20, and second snap-fit arm 63 is configured to bereleasably connected to locking recess 64 of second supporting member14. To this end, second snap-fit arm 63 includes a snap-fit detent 71.The first snap-fit arm 61 also includes a snap-fit detent (not shown).The snap-fit detent of snap-fit arm 61 is substantially identical tosnap-fit detent 71 of snap-fit arm 63. Locking recesses 58, 64 eachinclude an engagement wall 67, 69 (FIGS. 2 and 3). Each engagement wall67, 69 is configured to engage first and second snap-fit detents 63, 71to secure expansion member 16 to first and second supporting members 12,14. To release expansion member 16 from first and second supportingmembers 12, 14, a user pivots first and second snap-fit arms 61, 63about the cantilevered end away from engagement walls 67, 69 in order todisengage snap-fit detents 65, 71 from engagement walls 67, 69.

With continued reference to FIG. 3, second supporting member 14 includesan elongate body 70 defining a longitudinal passage 72 and a secondsupporting end 74. Elongate body 70 additionally includes a rectangularaperture 77 leading to longitudinal passage 72. Longitudinal passage 72is dimensioned to slidably receive elongate body 18 of first supportingmember 12 and is configured to receive bone support matrix. Secondsupporting end 74 includes a plurality of teeth 76 (FIG. 6) configuredto engage tissue. As seen in FIG. 6, teeth 76 are arranged inlongitudinal rows spanning the width of second supporting end 74. Eachtooth 76 defines an oblique angle relative to the second supporting end74, as shown in FIG. 4. Second supporting end 74 further includes arecess 78 (FIG. 6) disposed around a central area thereof. Recess 78 isadapted to receive bone support matrix therein. Additionally, secondsupporting end 74 includes at least one hole 80 (FIG. 6) located inrecess 78. Hole 80 provides access to longitudinal passage 72. In use,bone support matrix migrates from recess 78 to longitudinal passage 72through hole 80. In the depicted embodiment, second supporting end 74contains six (6) holes 80 having circular cross-sections and arranged inlongitudinal rows (FIG. 6). Second supporting end 74, however, mayinclude more or fewer holes 80 having different configurations andarrangements.

With reference to FIGS. 1, 4, and 7, second supporting member 14additionally includes cavities 82, 84 positioned on opposite lateralsides 86, 88. Each cavity 82, 84 is adapted to receive arms 118 ofinsertion tool 100. (See FIG. 10). Second supporting member 14 also hasholes 90, 92 on each lateral side 86, 88. Hole 90, which is located onlateral side 86, provides pin 40 access to slot 38, whereas hole 92,which is positioned on lateral side 88, provides pin 36 access to slot34. (See FIG. 9). Moreover, second supporting member 14 contains anopening 94 (FIG. 7) leading to longitudinal passage 72 and anotheropening 96 (FIG. 7) leading to rack 66. (See also FIG. 9). Opening 94includes an inner thread 95 (FIG. 1) and is adapted to receive pin 120of insertion tool 100 (see FIG. 14). Further, opening 96 is configuredto receive head 122 of insertion tool 100 (see FIG. 12) and threaded tip414 of insertion tool 400 (FIG. 37). Openings 94, 96 are positioned on afront surface of second support member 14, as seen in FIG. 7.

Referring to FIGS. 10 and 11, insertion tool 100 includes an insertionportion 102 for expanding and positioning expandable cage 10 and adriver 104 for adjusting the relative position of first and secondsupporting members 12, 14. Insertion portion 102 includes an elongatemember 110 defining a longitudinal axis “A” and a handle 106. Elongatemember 110 has a tapered section 110 t. Handle 106 extends transverselyfrom a proximal portion 110 p of elongate member 110. Driver 104includes an elongate member 112 defining a longitudinal axis “B” and ahandle 108. Handle 108 extends from a proximal portion 112 p of elongatebody 112. Longitudinal axis “B” defines an oblique angle relative tolongitudinal axis “A.”

Referring to FIGS. 10-14, a holding portion 114 interconnects insertionportion 102 and driver 104. Specifically, a distal end 110 d of elongatemember 110 is fixedly attached to holding portion 114, and a distal end112 d of elongate member 112 is rotatably connected to holding portion114. Holding portion 114 includes a bore 116 for receiving distal end112 d of elongate member 112 and a pair of arms 118 adapted to bereceived within cavities 50, 52 of first supporting member 12 orcavities 82, 84 of second supporting member 14. (See FIGS. 1-4). Distalend 112 d of elongate member 112 has a head 122 with a plurality ofteeth 124 (FIG. 14). Head 122 is configured to be received withinopening 96 of second supporting member 14. Teeth 124 are configured toengage rack 66. In operation, the rotation of head 122 causes the linearmotion of rack 66. Holding portion 114 further includes a pin 120protruding distally therefrom. Pin 120 is adapted to be received withinopening 94 of second supporting member 14.

In operation, a user employs insertion tool 100 to position expandablecage 10 between adjacent vertebrae and to move first and secondsupporting members 12, 14 relative to each other to expand expandablecage 10. Initially, the user holds expandable cage 10 with insertiontool 100 by placing arms 118 within cavities 82, 84, pin 120 throughopening 94 of second supporting member 14, and head 122 through opening96 of second supporting member 14. After removing diseased vertebraltissue from the patient, the user advances insertion tool 100 toward thedesired surgical site and places expandable cage 10 in the preparedspace between vertebrae. Once expandable cage 10 has been positioned inthe desired location, the user moves either first or second supportmember 12 or 14 relative to the other to adjust the height of expandablecage 10. To slide first and second support members 12, 14 with respectto each other, the user rotates driver 106. As driver 106 rotates, teeth124 of head 122 engage rack 66 and cause first and second supportmembers 12, 14 to move apart longitudinally with respect to the other.Once the desired relative position of first and second supportingmembers 12, 14 has been attained, the user places expansion member 16between first and second supporting members 12, 14 to fix their relativeposition. The user is provided with expansion members 16 of differentsizes. The user utilizes the expansion member 16 most suitable toachieve the desired expandable cage 10 height. As expandable member 16is inserted between first and second support members 12, 14, lockingportion 60 engages locking recesses 58, 64 and secures expansion member16 to first and second supporting member 12, 14. Recesses 46, 78 may bepacked with bone support matrix prior to insertion of expandable cage10, and longitudinal recess 22 may be packed with bone support matrixmaterial after expandable cage 10 has been positioned. Bone supportmatrix material may be added to expandable cage 10 through aperture 77.FIGS. 15-20 show another embodiment of the presently disclosedexpandable cage 200. The construction and operation of expandable cage200 is substantially similar to the construction and operation ofexpandable cage 10. In the interest of brevity, the present disclosurediscusses the differences between expandable cage 200 and 10. Identicalor similar reference characters designate similar or identical elementsin expandable cage 10 and expandable cage 200.

With continued reference to FIGS. 15-20, expandable cage 200 includes anexpansion member 16 substantially similar to expansion member 16 ofexpandable cage 10. However, expansion member 16 of expandable cage 200includes a threaded bore 273 (FIG. 20) in lieu of opening 73 (FIG. 3) ofexpansion member 16 of expandable cage 10. Threaded bore 273 extendsthrough locking portion 60 of expansion member 16 and includes an innerthread 275 (FIG. 20) adapted to mate with a threaded tip 314 ofinsertion tool 300 (FIG. 24). Elongate body 70 of second supportingmember 14 has a rectangular aperture 277 substantially similar torectangular aperture 77 (FIG. 2). The cross-sectional area ofrectangular aperture 277 is smaller than the cross-sectional area ofrectangular aperture 77 (FIG. 2).

With reference to FIG. 19, second supporting end 74 of second supportingmember 14 includes an elliptical opening 278 instead of recess 78 (FIG.6) of expandable cage 10. Elliptical opening 278 is disposed around acentral area of second supporting end 74 and is adapted to allow accessof bone support matrix into longitudinal passage 22.

Referring to FIG. 18, first supporting end 20 of first supporting member12 includes an elliptical opening 246 instead of recess 46 (FIG. 8) ofexpandable cage 10. Elliptical opening 246 has a smaller cross-sectionthan elliptical opening 278 of second supporting end 74 (FIG. 18). Inaddition, elliptical opening 246 is disposed around a central area offirst supporting end 20 and is adapted to allow access of bone supportmatrix into longitudinal passage 22.

As seen in FIGS. 21 and 22, first, second and third walls 28, 30, 32 ofelongate body 18 have rounded outer surfaces as opposed to flat outersurfaces. First, second, and third walls 28, 30, 32 still collectivelydefine longitudinal passage 22. As shown in FIGS. 21-23, expansionmember 16 includes a locking portion 60 and pair of legs 62 extendingtransversely from locking portion 60. Each leg 62 includes a round innersurface 279 configured to mate with the rounded outer surfaces of walls28, 32. Expansion member 16 of expandable cage 200 further includes athreaded hole 276 disposed through locking portion 60 and an innerthread 275 formed around threaded hole 276. Inner thread 275 is adaptedto mate with an external thread 315 (FIG. 27) of threaded tip 314 of adriver 300.

FIGS. 24 and 25 illustrate another embodiment of a driver 300 foradjusting the relative position of first and second supporting members12, 14. Driver 300, which is configured to be used in conjunction withinsertion tool 400 (FIG. 36) or any other suitable insertion tool,includes a handle 302, a holding portion 304, and an elongate portion306 interconnecting handle 302 and holding portion 304. Elongate portion306 extends distally from handle 302 and defines a longitudinal axis“C.” Holding portion 304 includes first and second arms 308, 310extending distally therefrom, as seen in FIG. 25. First and second arms308, 310 define a gap therebetween. In addition, holding portion 304includes a distal opening 312 for exposing a threaded tip 314 of driver300. Distal opening 312 is disposed in communication with a bore 316extending through elongate portion 306. Bore 316 is configured toaccommodate a tubular member 318.

With reference to FIGS. 26 and 27, driver 300 further includes tubularmember 318 having a longitudinal opening 320. Longitudinal opening 320extends through tubular member 318 and is dimensioned to receive a rod322. Rod 322 includes a threaded tip 314 located at a distal end 324thereof. Threaded tip 314 includes an external thread 315 adapted tomate with inner thread 275 of threaded hole 273 of expansion member 16(FIG. 20). A proximal end 326 of rod 322 is attached to a knob 328. Knob328 allows a user to rotate rod 322.

Referring to FIGS. 29-31, handle 306 defines a bore 330 dimensioned toreceive a proximal section 332 of elongate portion 306. Proximal section332 of elongate portion 306 has a diameter that is larger than thediameter of the rest of elongate portion 306. Moreover, proximal section332 of elongate portion 306 includes first and second flat surfaces 334,336. First and second flat surfaces 334, 336 are disposed in adiametrically opposed relation relative to each other and arecollectively configured to retain a distal portion 340 of a biasingmember 338. In one embodiment, biasing member 338 is a coil spring, butbiasing member 338 may be any suitable mechanism, apparatus, means, ordevice. A proximal portion 342 of biasing member 338 abuts an annularinternal surface 344 of handle 306. Biasing member 338 biases rod 322 ina distal direction. A plurality of pins 346, or any other suitableapparatus, secures handle 306 to tubular member 318 and elongate portion306.

As seen in FIG. 31, rod 322 is slidably positioned in longitudinalopening 320 of tubular member 318. Tubular member 318, in turn, isslidably disposed in bore 316 of elongate portion 306. As discussedabove, biasing member 338 biases rod 322 distally so that at least aportion of threaded tip 314 is located outside of bore 316.

As seen in FIGS. 32-33, driver 300 can be employed, among other things,for holding and inserting expansion member 16 of expandable cage 200between first and second supporting members 12, 14. As discussed above,expansion member 16 of expandable cage 200 includes a threaded bore 273having inner thread 275 (FIG. 20), and driver 300 includes a threadedtip 314 having an external thread 315. Inner thread 275 is adapted tomate with external thread 315 of threaded tip 314. In operation, a userinserts at least a portion of threaded tip 314 of driver 300 in threadedhole 237 of expansion member 16. At this moment, first and second arms308, 310 abut an upper surface of expansion member 16, as seen in FIG.34. Then, the user rotates rod 322 (FIG. 26) via knob 328 to rotatethreaded tip 314. In response to the rotation of threaded tip 314,external thread 315 of threaded tip 314 threadably engages inner thread275 of threaded hole 237, thus securing expansion member 16 to driver300. After expansion member 16 has been secured to driver 300, the useradvances driver 300 toward first and second supporting members 12, 14and places expansion member 16 between first and second supportingmembers 12, 14. As discussed in detail below, driver 300 can also beused in conjunction with insertion tool 400 (FIG. 36) which displacesfirst and second supporting members 12, 14 relative to each other inpreparation to receive expansion member 16.

FIGS. 36 and 37 show an insertion tool 400 designed for insertingexpandable cage 10 inside into a prepared space in the body.Specifically, a user may utilize insertion tool 400 to place expandablecage 10 between vertebrae. Insertion tool 400 generally includes ahandle 402, an elongate section 404 oriented transversely relative tohandle 402, and a holding section 406 attached to a distal portion 408of elongate section 404. Handle 402 facilitates gripping by a user andis operably coupled to a proximal portion 410 of elongate section 404.

As depicted in FIG. 37, holding section 406 is adapted to holdexpandable cage 10 and includes a hexalobular head 412 rotatably mountedthereon, a threaded tip 414 also rotatably mounted thereon, and firstand second arms 416, 418 extending distally therefrom. Hexalobular head412 includes teeth 420 each configured to engage undulations 42 of rack66 of first support member 12 (FIGS. 3 and 9). As discussed in detailbelow, rotating hexalobular head 412 when teeth 420 are engaged withundulations 42 of rack 66 causes first and second supporting members 12,14 to move relative to each other. Threaded tip 414 is dimensioned to bereceived within opening 94 and includes an external thread 422 formedthereabout. External thread 422 of threaded tip 414 is adapted to mateinner thread 95 of opening 94 of first support member 12 (FIG. 1) tosecure holding section 406 of insertion tool 400 to expandable cage 10(FIG. 1). First and second arms 416, 418 define a gap therebetween. Eachof first and second arms 416, 418 is configured to be received incavities 82, 84 of expandable cage 10 (FIGS. 1 and 4). When first andsecond arms 416, 418 are positioned in cavities 82, 84 of expandablecage 10 (FIGS. 1 and 4), holding section 406 retains expandable cage 10.

With reference to FIGS. 38-40, insertion tool 400 includes a rod 424slidably disposed through elongate section 404. Elongate section 404 hasa longitudinal opening 426 extending therethrough. Longitudinal opening426 of elongate section 404 is dimensioned to slidably receive rod 424.Rod 424 has a proximal portion 428 and a distal portion 430. A knob 432is attached to proximal portion 428 of rod 424. Distal portion 430 ofrod 424 is connected to threaded tip 414.

As seen in FIG. 40, elongate section 404 includes a thread 434 disposedaround distal portion 408. Thread 434 is adapted to mate with an innerthread 436 of holding section 406. When thread 434 of elongate section404 mates with inner thread 436 of holding section 406, elongate section404 attaches to holding section 406.

As illustrated in FIG. 40, holding section 406 includes a first bore 438dimensioned to receive distal portion 430 of rod 424, at least part ofdistal portion 408 of elongate section 404, and threaded tip 414.Holding section 406 further includes a thread 440 formed around aportion of first bore 438. Thread 440 is adapted to mate with thread 434of rod 424 to fix the position of rod 424 relative to holding section406.

With reference to FIGS. 41-45, holding section 406 includes a secondbore 442 oriented at an oblique angle relative to first bore 438 (FIGS.38 and 40). Second bore 442 is dimensioned to slidably receive a bar444. Bar 444 has a proximal portion 446 and a distal portion 448. Distalportion 448 of bar 444 is attached to hexalobular head 412, and proximalportion 446 of bar 444 is connected to a cylindrical member 450.Cylindrical member 450 includes a socket 452 configured to receive andengage threaded tip 314 of driver 300 as described in greater detailbelow with reference to FIGS. 49-53. Bar 444 is rotatably disposed inbore 442 such that, when threaded tip 314 of driver 300 engages socket452, rotating threaded tip 314 causes the rotation of bar 444. Holdingsection 406 further includes a biasing member 454, such as a spring,partially positioned inside bore 442. Biasing member 454 includes aproximal end 456 attached to cylindrical member 450 and a distal end 458abutting an inner annular wall 460 of holding section 406. In operation,biasing member 454 biases bar 444 proximally.

With reference to FIGS. 46 and 47, insertion tool 400 further includes acoupling member 460 for connecting handle 402 to elongate section 404.Coupling member 460 includes a tubular portion 462 and shaft 464extending transversely from tubular portion 462. As shown in FIG. 46,tubular portion 462 defines a longitudinal opening 466 extendingtherethrough. Longitudinal opening 466 is configured to receive at leastpart of proximal portion 410 of elongate section 404 and at least partof proximal portion 428 of rod 424. A biasing member 468, such as aspring, partially surrounds proximal portion 428 of rod 424 and has aproximal end 470 and a distal end 472. Proximal end 470 of biasingmember 468 abuts an annular wall 474 located on proximal portion 428 ofrod 424. Distal end 472 of biasing member 468 is attached to proximalportion 410 of elongate section 404. Biasing member 468 is disposed inlongitudinal opening 466 of tubular portion 462, and in operation,biases rod 424 in a proximal direction.

As seen in FIG. 47, shaft 464 of coupling member 460 is positionedinside handle 402. A pin 476, or any other suitable device, apparatus,or means, couples handle 406 to shaft 464, thereby connecting handle 402to coupling member 460. Shaft 464 includes a hole 478 adapted to receivepin 476. Handle 402 also includes a hole 480 adapted to receive pin 476.When pin 476 is inserted through hole 480 of handle 402 and hole 478 ofshaft 464, pin 476 interconnects handle 402 and coupling member 460.

With continued reference to FIGS. 46 and 47, insertion tool 400additionally includes a plurality of pins 482 for connecting rod 424 toelongate section 404. (See also FIG. 46). Rod 424 includes a depressedarea 484 having a smaller diameter than the surrounding portions of rod424. When insertion tool 400 is assembled, pins 482 seat ondiametrically opposed sides of depressed area 484 to secure rod 424 toelongate section 404. (See FIG. 46).

With reference to FIG. 48, bar 444 of holding section 406 includes aplurality of teeth 486 protruding proximally from proximal portion 446.Teeth 486 are disposed annularly on a proximal surface 492 (FIG. 41) ofbar 444 and are oriented at an oblique angle with respect to bar 444.Holding section 406 defines a recess 488 dimensioned to fixedly receivea tab 490. Tab 490 includes a plurality of teeth 494 adapted to engageteeth 486 of bar 444. Teeth 494 of tab 490 are disposed annularly on abottom portion of a distal surface 946 of tab 490 and are oriented at anoblique angle with respect to tab 490. The orientations of teeth 486 and494 allow bar 444 to rotate in one direction, while inhibiting orprecluding rotation of bar 444 in the opposite direction.

Referring to FIGS. 49-53, a user can employ driver 300 and insertiontool 400 to place and expand expandable cage 10 in the desired surgicalsite. First, the user positions holding portion 406 of insertion tool400 on expandable cage 10 so that first and second arms 416, 418 (FIG.37) are disposed in cavities 82, 84 (FIGS. 4 and 5). While first andsecond arms 416, 418 are placed in cavities 82, 84, hexalobular head 412of insertion tool 400 passes through opening 96 (FIG. 7) of expandablecage 10 to reach rack 66, and threaded tip 414 of insertion tool 400(FIG. 37) passes through opening 94 (FIG. 7) of expandable cage 10.Whilst inserting threaded tip 414 of insertion tool 400 into opening 94of expandable cage 10, the user rotates rod 424 via knob 432 tothreadably engage thread 422 of threaded tip 414 to thread 95 of opening94, thereby fixing holding section 406 of insertion tool 400 toexpandable cage 10 (FIG. 52).

After securing insertion tool 400 to expandable cage 10, the useradvances insertion tool 400 toward the desired surgical site to positionexpandable cage 10 in a space between vertebrae. Once expandable cage 10has been positioned between the vertebrae, the user moves first andsecond supporting members 12, 14 relative to each other to adjust theheight of expandable cage 10. In order to displace first and secondsupporting members 12, 14 relative to each other, the user firstpositions threaded tip 314 of driver 300 (FIGS. 24 and 25) into socket452 of insertion tool 400. Next, the user rotates rod 322 of driver 300through knob 228 to urge the rotation of hexalobular head 412. Ashexalobular head 412 rotates while engaging rack 66, first and secondsupporting members 12, 14 move apart relative to each other to adjustthe height of expandable cage 10. The user adjusts the height ofexpandable cage 10 until a first supporting end 20 and second supportingend 74 engage the vertebral bodies of adjacent vertebrae.

Subsequently, the user detaches driver 300 from insertion tool 400 andholds expansion member 16 with driver 300 as discussed in detail above(See FIGS. 32-35). The user then advances driver 300 toward expandablecage 10 to position expansion member 16 between first and secondsupporting members 12, 14. As expansion member 16 is placed betweenfirst and second supporting members 12, 16, locking portion 60 ofexpansion member 16 engages locking recesses 58, 64 (FIG. 3) to fixexpansion member 16 to expandable cage 10. Once expansion member 16 hasbeen secured to first and second supporting members 12, 16, expansionmember 16 maintains the relative position of first and second supportingmembers 12, 14 of expandable cage 10. Optionally, the user packs thespace between adjacent vertebrae with bone support matrix.

It will be understood that various modifications may be made to theembodiments of the presently disclosed expandable cage and insertiontool. Therefore, the above description should not be construed aslimiting, but merely as exemplifications of embodiments. Those skilledin the art will envision other modifications within the scope and spiritof the present disclosure.

What is claimed is:
 1. An apparatus for spinal surgery, comprising: anexpandable cage including: a first supporting member having a rackextending along an inner surface thereof, the rack including undulationsthat are configured and dimensioned to engage a head of an insertiontool, and a second supporting member having a longitudinal passagedimensioned to receive a portion of the first supporting member, thefirst and second supporting members configured to move relative to eachother; an expansion member having a backspan with first and second legsextending therefrom, the expansion member positionable between the firstand second supporting members and adapted to maintain the first andsecond supporting members in a fixed relationship, the first legdisposed on one side of the rack and the second leg disposed on anopposed side of the rack; and a locking portion disposed on the backspanof the expansion member, the locking portion configured to maintain theexpansion member in engagement with the expandable cage.
 2. Theapparatus of claim 1, wherein each of the first and second supportingmembers includes a locking recess configured to securely receive thelocking portion of the expansion member.
 3. The apparatus of claim 2,wherein the expansion member includes a threaded bore configured tothreadably engage a threaded tip of an insertion tool.
 4. The apparatusof claim 1, wherein the locking portion includes a movable cantileveredarm that is transitionable between a first position that engages one ofthe first or second supporting members and a second position that isdisengaged from one of the first or second supporting members.
 5. Theapparatus of claim 1, wherein the fixed relationship is defined bycontact of the expansion member with the first and second supportingmembers.
 6. The apparatus of claim 5, wherein the expansion member hasopposed first and second outer surfaces that respectively engage thefirst and second supporting members.
 7. The apparatus of claim 1,wherein the second supporting member has an opening through an outerwall thereof for receiving a head of an insertion tool.